The present invention relates to plastic adhesive labels for glass and plastic substrates and plastic adhesive films suitable for making such labels comprising polyethylene. Labels of the present invention can be applied to glass or plastic containers such as bottles and jars prior to the filling of the containers and can survive rinsing, filling, and pasteurization operations as well as consumer end-use applications (e.g. immersion in an ice chest), or can be applied after the containers have been filled.
Currently, most glass and plastic containers are labeled with paper labels. These paper labels can not withstand the processes that the containers must go through. Thus, to avoid damage to the paper labels, the paper labels are applied to a container after the processing steps (i.e., xe2x80x9cpost-appliedxe2x80x9d). Generally, printed paper labels are post-applied to filled containers using aqueous adhesives or hot melt adhesives.
If post-applied paper labels are not completely adhered to the bottle, are misaligned on the bottle, or are otherwise incorrectly applied to the filled bottle, then the entire container and contents will be unusable and must be discarded. Thus, it is desired that containers be labeled and inspected prior to being filled to avoid discarding the contents of containers along with those containers requiring discard due to defective labels.
It is known in the art to use certain high performance acrylic pressure sensitive adhesives to pre-apply plastic labels to containers following container formation at a container manufacturing plant. Examples include Optiflex labels (available from and a trademark of Flexcon), Clear Advantage labels (available from and a trademark of Avery), and Primeline label films (available from and a trademark of the Polykote Corporation). These labels can generally withstand the container processing operations at a container filling plant. Thus, these labels have overcome some of the deficiencies of a post-applied label.
However, the high performance acrylic pressure sensitive adhesives are costly. Labels made using high performance acrylic adhesives generally cost 3-5 times as much as paper labels. This increased cost inhibits widespread market acceptance.
It is also known in the art to use oriented polypropylene and polyethylene terepthalate pressure sensitive labels to apply to containers. These materials have worked well due to their stiffness and clarity, however these materials tend to be difficult to cut into specific shapes. On occasion, edge stringers or insufficient edge cut have been observed.
Film compositions including polyethylene are known in the art. U.S. Pat. No. 6,150,013 discloses an in-mold label film comprising at least two layers with one layer being a heat seal layer for bonding the film to a polymer substrate wherein the film has a thermal conductivity of less than about 1.250xc3x9710xe2x88x924 k-Cal/sec cmxc2x0 C. The invention further includes a process for in-mold labeling comprising the steps of forming a label comprising at least two layers with one layer being a heat seal layer for bonding the film to a plastic substrate wherein the film has a thermal conductivity of less than about 1.250xc3x9710xe2x88x924 k-Cal/sec cm xc2x0 C., inserting the label into a mold for producing the plastic substrate with an inside and outside surface thereafter forming a plastic substrate in the mold with sufficient heat wherein the outside surface of the substrate bonds with the heat seal layer of the label. U.S. Pat. No. 6,150,013 is incorporated herein by reference in its entirety.
U.S. Pat. No. 6,136,439 discloses a monolayer printable polymeric film and method for making the film. The film is formed by mixing a structural material, such as polypropylene or polyethylene, with a printable material, such as vinyl-acetate or methacrylate, to form a unitary mixture prior to processing. The unitary mixture is extruded and heated so as to cause the printable material to bloom to the surface of the unitary mixture. Stretching of the mixture at temperatures greater than permissible for multi-layered films formed of separate structural and printable materials heat sets and relaxes or stress relieves the film that is formed. The result is a monolayer film that is stiffer and that lays much flatter than the prior multi-layered films that were prone to curling. The mixture is preferably heated to 270xc2x0 F. or greater during the stretching process. U.S. Pat. No. 6,136,439 is incorporated herein by reference in its entirety.
U.S. Pat. No. 6,127,032 discloses a multilayer film useful for making plastic adhesive labels for glass substrates such as glass bottles. The multilayer films contain a base layer, an adhesive layer, and optionally an intermediate layer to improve interlayer bonding between the base layer and the adhesive layer. The adhesive layer comprises a heat-activated thermoplastic adhesive that is not tacky at room temperature. Films of the present invention are sufficiently non blocking at room temperature so as to not require the use of a separate release liner. The film can be utilized in conventional graphics printing operations and made into labels. Labels made from films of the present invention can be thermally adhered to glass substrates and exhibit sufficient adhesion to glass substrates to withstand washing/rinsing, filling, and pasteurization processes utilized in the bottling industry. U.S. Pat. No. 6,127,032 is incorporated herein by reference in its entirety.
U.S. Pat. No. 6,004,682 discloses an oriented polymeric in-mold label film that comprises a hot-stretched, annealed, linerless self-wound film lamina and has a face layer for printing and a base layer which includes a heat-activatable adhesive. The heat-shrinkability of the film is balanced thickness-wise to minimize curl and allow the film to be printed in conventional label-printing presses. An antistat may be included only in the charge for the base layer which includes the heat-activatable adhesive. In the manufacture of labelled blow-molded containers, sheets and labels formed from the film may be handled at high speeds while maintaining accurate registration and dimensional and positional integrity even in the absence of any reinforcing backing, yet the labels perform well on deformable containers such as shampoo bottles. U.S. Pat. No. 6,004,682 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,985,075 discloses a film-forming means that is coextruded to form all plastic multilayer liners and facestocks for pressure-sensitive labels, tapes, decals, signs, bumper stickers, and other products formed from sheet and roll stock. The film materials of the layers of the constructions are selected according to the cost/benefit characteristics of candidate materials considering the functional or operational requirements of the layer in question. U.S. Pat. No. 5,985,075 is incorporated herein by reference in its entirety.
U.S. application Ser. No. 09/307,011 discloses a matte surface film comprising: (a) a base layer comprising high density polyethylene (HDPE); and (b) a matte surface layer comprising a blend of two or more incompatible polyolefins. In preferred embodiments, the matte surface layer comprises (i) a propylene homopolymer or propylene interpolymer and (ii) an ethylene homopolymer or ethylene interpolymer. The film possesses easy and improved cuttability and may be used for packaging and label applications. U.S. application Ser. No. 09/307,011 is incorporated herein by reference in its entirety.
The present invention provides multilayer plastic films that are particularly suited for manufacturing plastic labels for glass and plastic substrates. Films of the present invention exhibit a number of properties that make them particularly suitably for manufacture into labels for glass and plastic substrates.
Films of the present invention generally comprise a base layer and an adhesive layer bonded to the base layer. The adhesive layer may be bonded directly to the base layer or an intermediate tie layer may be used between the base layer and the adhesive layer to improve interlayer bonding between the base layer and the adhesive layer.
Plastics which can usefully comprise the base layer include high density polyethylene (xe2x80x9cHDPExe2x80x9d). Preferably, the base layer in films and labels of the present invention is made of oriented high density polyethylene (xe2x80x9cOHDPExe2x80x9d).
In another embodiment of the present invention, multilayer films of the present invention can be printed on and cut into adhesive labels for adhering to glass and plastic containers. Adhesive labels of the present invention can be laminated with pressure to glass and plastic bottles.
Advantages of the invention include one or more of the following:
a film that exhibits sufficient tensile strength, modulus, tear resistance and flatness to allow it to be easily handled in a graphics printing operation;
a film that exhibits sufficient adhesion to printing ink such that the ink is not wiped, peeled, or abraded off of the film surface during the printing operation;
a film that exhibits excellent adhesion to glass and plastic substrates;
a film that will adhere to glass and plastic and provide a water and moisture resistant bond to the substrate;
a film that exhibits good surface printability, as is, treated, or through surface coating;
a film that exhibits sufficient stiffness for die cut and dispensing;
a film that exhibits adhesive compatibility so that it can be used in a PSA sandwich structure;
a film that is clear;
a film that is white;
a film surface that is smooth;
a film surface that is matte;
a film that exhibits good ink registration for printing multi-color;
a film that exhibits water/moisture resistance;
a film that is difficult to tear.